Pre-flare dynamics of chromospheric structures and magnetic field in the active region NOAA 9077

The object of the study was the active region (AR) NOAA 9077, which produced three flares of importance X. At Baikal Observatory, the observations of full disc solar chromosphere in H-alpha line with Halle birefringent filter, were carried out on July 10-14. The magnetograms of the AR, of Beijing Observatory, were used as additional data. A characteristic property of the AR 9077 evolution was the emergence of new magnetic flux on July 10-11 and the absence of any indications thereof on July 12-14 prior to a powerful flare. However, another process of fast changes in the magnetic field was revealed - magnetic cancellation, which proceeded at about the same rate as did the new flux emergence. The magnetic flux imbalance increased towards south polarity predominance during July 10-12, followed by its fast decrease before the major flare. The flares were preceded by fine structure of chromosphere changes.